It is known that forest machines include various harvesters, forwarders and combinations of these, which are also called combi machines. In this description, such combi machines are also included when harvesters are mentioned, if the function in question is similar to the function in a harvester. It is known that control systems are used for controlling the forest machines. One control system of prior art is Timberjack Timbermatic 300, which is a system for controlling the functions of a forest machine and particularly a harvester head, and for measuring and bucking of timber. In the forest machine, the control system controls, among other things, the diesel engine, the hydrostatic drive transmission, the harvester head and the crane system, to which the harvester grapple is coupled, as well as all the auxiliary functions related to these. The control system in question operates, for example, in the PC/Windows 2000 operating environment. In the bucking instructions of the control system it is possible to include, for the timber to be processed, for example value, distribution and colour marking matrices, groups of types of timber, and trunk types. By means of an application included in the Timbermatic 300 system, it is possible to analyze and compute the production results, such as the number, length and diameter of logs, the distribution levels, the groups of types of timber, and the trunk types.
The control system controls, for example, the harvester grapple in such a way that the control of the feeding of a log will automatically adjust the feeding speed and the pressure of the feed rolls and the delimbing blades, and that an anti-slip function will prevent the slipping of the feed rolls and make it possible to stop the tree trunk accurately for the sawing.
The display and the central processing unit of the control system are placed in the cabin, within reach for the driver. Normally, the system also comprises a printer.
The control bus in the control and measuring automatics of the control system is based on a CAN bus solution of prior art, in which data is passed in digital form. In the control bus, measurements and signals are transmitted in a way known as such. On the basis of the data, it is possible to monitor measurements relating to the duration and functional speeds of different steps in the processing. From the signals and measurements, information is obtained about the functional times and timings of components responsible for various functions. The components may be, for example, for the functions of the crane system or the harvester head connected to it, such as feeding, diameter measurement, length measurement, sawing, and delimbing. The processing of a single tree trunk involves a large number of measurement values that may be stored in a database which further comprises a classification, for example, on the basis of size classes of trunks and logs. The size class of the trunk is known on the basis of the measurement values.
Reduced technical performance of a forwarder, a harvester, or a harvester grapple, both in the overall system and its subsystems and constituent functions, will impair the profitability of the harvesting work. It has been difficult to detect a long-term reduction in the performance, because it has been based on, for example, the subjective evaluations and experiences by the operator or the maintenance personnel and servicemen, which may be limited in time and relate to some individual forest machines only. Furthermore, it has been impossible to evaluate effects caused by repair and change works or changes in working methods in a reliable way.
For example, it has not been previously possible to monitor the condition of the sawing function or the feeding function of a harvester in a reliable way. In solutions of prior art, for example the sawing times are compared with fixed alarm limits, and when the limit is exceeded, a warning message is displayed to the driver. However, the performance of the sawing system or, on the other hand, of the feeding function is one of the most important factors on the output of the harvester. Reduced performance will reduce the profitability of the harvesting work, and if continued, a failure may result in subsequent damage that is worse than before, and in a production break.
Moreover, it has not been previously possible to monitor the condition of stem holding by the harvester grapple. Stem holding by the harvester grapple is an important factor on the output as well as on the measuring accuracy of the harvester. Impaired stem holding will reduce the profitability of the harvesting work. For example, if the clamping by the delimbing blades is insufficient, the tractive force of the bed rolls will not be transmitted efficiently to the trunk, and on the other hand, the accuracy of measurement of the diameter will be impaired. The accuracy of measuring the length will also be impaired, because contact faults between the measuring reel and the trunk will increase. If the clamping by the delimbing blades is too tight, the frictional force between the blades and the trunk will become too great. Thus, the feeding speed and output of the grapple will reduce, and the fuel consumption will increase.
It has not been previously possible to measure the output of a forest machine in such a way that the measurement would be useful in the monitoring of the performance and particularly the condition of the forest machine. A sufficiently high output of the harvester, that is, a large quantity of timber processed in cubic meters per hour (m3/h), is a basic requirement for economically viable mechanized harvesting. However, the output of the harvester may be reduced for a number of reasons, such as malfunctions or machine settings that are not suitable for the conditions.
Furthermore, it has not been previously possible to measure the fuel consumption of a forest machine in such a way that the measurement would be useful for monitoring the condition of the machine. Previously, a direct consumption per hour has been measured, which is not sufficient for evaluating the condition of the forest machine and for monitoring the performance in long term.
As to the drive transmission of the forest machine, i.e. the forwarder and the harvester, the number of operating hours has been monitored, which is, however, not sufficient for monitoring the condition and determining the need for maintenance more closely. Similarly, it has not been possible to monitor the condition of the crane system of the harvester or forwarder sufficiently accurately.